Preheat oven to 350F (180C).,______,Melt the butter in a saucepan over medium-low heat.,Whisk in the flour, then add the milk, salt and peppers.,Stir constantly until the mixture thickens and is smooth, 8 to 10 minutes.,Add the cheese and cook, stirring, until it melts.,In a mixing bowl, combine the macaroni and the sauce.,Stir in the tomatoes and sugar.,Transfer macaroni mixture to the baking dish.,BAke until the surface browns, 30 to 40 minutes.